The invention relates to a method of adjusting an implantable heart stimulator in dependence on the effort exerted by the patient wearing the stimulator, using an external control programmer associated in operation with the stimulator, an implantable heart stimulator having parameters adjustable in dependence on the effort exerted by the patient, and an external programmer for actuating an implantable heart stimulator so as to adjust the operating parameters of the stimulator, which comprises receiving means for coupling to the programmer.
Known adjustable heart stimulators (French PSS 2 379 104, 2 383 674, 2, 471 789, 2 431 296, 2 424 737, 2 342 722, 2 374 024, 2 550 095, 2 516 797, European PS 96 464, U.S. Pat. No. 3,867,950) are of one of the following two kinds, externally controlled or internally controlled, the two kinds not being exclusive of one another.
Known external control is brought about via an external programmer, usually by the doctor, and the aim is to adapt when necessary (usually occasionally) the various parameters of the stimulator (the stimulation period, width of stimulation pulse, amplitude of stimulation pulse, sensitivity of amplifier of stimulator, refractory period, escape period, etc.). In the first case, the programmer and the stimulator are designed so that the parameters can be adjusted separately and in succession. This adjustment takes time and requires supervision by the doctor, which is not troublesome in itself, since the adjustment is occasional. A typical embodiment of an aforementioned stimulator is described in French PS 2 427 737. Another typical example is a stimulator having two switchable speeds; a powerful magnetic disposed opposite the place where the stimulator is implanted produces a magnetic field so as to flip the stimulator from a first operating speed to a second operating speed and thus adapt it to requirements. This embodiment has the advantage of simplicity but the disadvantage of being of limited range.
Known internal control is usually brought about automatically, depending on the state of the patient wearing the stimulator, via a parameter representing his state. There are various typical known embodiments: a stimulator actuated by auricular activity or the temperature of the venous flow or frequency of respiration or the distance between the R wave and the apex of the T wave of cardiac activity etc. These embodiments have the advantage of automatic adjustment but present numerous problems--unreliable maintenance of position of an auricular electrode for recording the auricular electric activity, defective correlation between the measured parameter and the values given to the operating parameter of the stimulator, and difficulties in accurately determining the position of the T wave etc. in dependence on the parameter under consideration.
There is also a known heart stimulator programmer (document FR 2481933) which can be operated by the patient himself, the programmer comprising a slider for selecting one out of three operating frequencies of the heart stimulator, or more specifically the frequency corresponding to a particular physiological need. However, this programmer has some disadvantages; the change from one to another frequency occurs abruptly, the patient risks forgetting the frequency at which his stimulator is operating, programmers are specific and non-interchangeable, the operating modes of the stimulator are undeveloped, the programmer can be forcibly misadjusted and altered, and the programmer in use has to be disposed opposite the stimulator, which is inconvenient. In short there is some risk in operation, and the equipment is expensive and unsophisticated.